5pSA5. Structure-borne sound power through multiple contact points between
machines and supporting structures.

The structure-borne sound emission from machines through multiple contact
points is highly influenced by the extent of coupling between these points.
When the machine is unconstrained (i.e., disconnected from the supporting
structure) the coupling can be assessed by comparing the point and transfer
mobilities of the machine. Once connected however, account must be made too of
the force distribution amongst the contact points. While the forces themselves
at the points are sensitive to the structural characteristics of the particular
installation, their distribution, which is most readily described by the ratios
of the contact point forces, may be less sensitive. Using combinations of real
and theoretical installations, force distributions have been investigated.
Studies have also been undertaken on the estimation and approximation of the
force ratios and their effect on the estimate of the total active power from
the machine to the supporting structure. It will be shown that this has
application to the characterization of structure-borne sound sources.